Strap tensioning device with extensometer



Feb. 1, 1966 E. c. RUTTY 3,232,583

STRAP TENSIONING DEVICE WITH EXTENSOMETER Filed Jan. 13, 1964 0O INVENTOR. EDWARD C. RUTTY BYM 7, ATTORNEYS United States Patent H 3,232,583 a STRAP rnrssrorsnso Dayton WITH EXTENSOMETER p M Edward C. Rutty, Portland, onn-., assignor to The Stanley Works, New Britain, Conn, a corporation er Corinect'icut Filed 3.111.713, 1964; Ser'. No. 337,493

4 Claims. (Cl. 254-"51) The present invention relates to strap tensioning devices having particular utility for tensioning nonmet'allic strapping, for example conventional nylon strapping, and more particularly relates to a' measuring rule useful in combination with a tensioning device for effecting control of the strap tension by providing a measure of the strap stain or elongation resulting from the strap tension.

It is a principal aim of the present invention to provide a readily useful measuring rule for a strap tensioning device for facilitating the control of the applied tension of the strap.

It is another aim of the present invention to provide an improved extensomete'r for a strap tensioning device which includes a measuring rule having indicia for alerting the operator when the strap has been suitably tension'ed and thereby prevent the application of excessive tension.

It is a further aim of the present invention to provide an improved measuring rule of the type described having an economical construction and which may be readily attached to conventional tensioning devices.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth, and the scope of the application of which will be indicated in the appended claims.

In the drawing:

FIG. 1 is a longitudinal side view, partly broken away,

' of an installation of a strap loop in a strap tensioning tool incorporating an accessory of the present invention;

FIG. 2 is an enlarged side view, partly broken away, of the accessory of FIG. 1 with parts removed;

FIG. 3 is an enlarged top longitudinal view, partly broken away, of the accessory of FIG. 1; and

FIG. 4 is an enlarged transverse side view of the fastener of the accessory of FIG. 1.

Referring now to the drawing in detail, the illustrated rap tensioning tool it) is of the type disclosed in my cop'ending application entitled, Feeding and Tensionin'g Tool for Strapping and the Like, filed September 10, 1963, and given Serial Number 308,014, now United States Patent No. 3,169,011, which issued February 9, 19 65. The tool It is adapted for receiving the overlapping portions of a loop of strap and is operable for forwardly feeding the outer overlapping portion of strap, to the left as seen in FIG. 1, and thereby tension or tighen the loop about an enclosed article. The tool includes a cast frame having a handle 11, a base 12 with rearward and forward strap platforms 1'6, 18, respectively, and a forward column 2% extending outwardly from the forward platform 18. A tension wheel housing 26 is pivotally mounted on the column 20 by a pivot pin 24 and a tension or feed wheel 28 is retained within the housing by a wheel drive shaft 29. The drive shaft is operatively connected via a ratchet macha'rlism (not shown) to an operating lever 35) provided for rotating the tension wheel 28, clockwise as seen in FIG. 1.

The illustrated strap tensioiiing tool is designed primarily for use with nonmetallic strapping, such as nylon 3,232,583 Patented Feb. 1, 1966 strapping, which in the usual form has a width and thickness approximately the same as conventional metallic strapping. For reasons more fully described in the aforementioned copendingap'plica'tt'ion',v the tensioningtool ineludes a support 34 intermediatethe tension wheel 28 and the forward platform 18-. Generally, however, the sup-- port 34 i s'loo'sely mounted in the column 20 immediately above the platform 18 whereby the outer overlapping portion of nonmetallic strap can be positioned between the tensio'ning wheel 28 and the support 34 and theinner overlapping portion of strap can be positioned between the support 34 and the plaform 18, for which purpose the tension wheel housing and tension wheel can be conveniently pivoted away from the support 34 against the bias of a torsion spring 4d, only partially shown. Feeding of the outer overlapping portion of strap is provided by repeated pivotal oscillation of the operating lever 30 with the inner overlapping portion of strap being restrained between the support 34 and platform 18, for which purpose the platform 18 may be provided with lateral serrations (not shown).

After the loop of strap has been appropriately tensioned, it can be suitably sealed as with a seal 46 and the free end of strap can be thereafter severed, which in the illustrated tool is accomplished at 36 by the coaction of a stationary cutting blade 47 and a pivotal cutting blade 48 manually actuated by a lever 56.

Because of the substantial mechanical advantage provided by the lever 3i), and inasmuch as with the usual nonmetallic strapping the elongation or stretching of the strap resulting from tensioning is considerably more than with metallic strapping, control of the applied tension in the nonmetallic strapping is more difiic'ult and the desired tension can be readily exceeded unintentionally and unknowingly. Moreover, the usual nonmetallic strapping when excessively tensioned tends to rupture only after some time delay. Such a delayed rupture not only results in a waste of material and labor but can also result in the not too remote possibility of damage to an article about which the ruptured strap had been applied.

In accordance with the present invention an accessory 60 for the tensioning tool is provided for indicating the tension in the loop of strap and selecting the desired tension and thereby preclude subsequent rupture of the strap. The accessory 60 functions as an ext'ensoineter and can be conveniently secured to the side of the strap tensioning tool, as illustrated, for which purpose the acces sory housing 62 may be attached to the tension wheel housing 26 by a threaded fastener 64 extending through the side of the accessory housing and by an elongated threaded fastener 66. The fastener 66 additionally provides in conjunction with a similar but shorter fastener 68 for attaching a cover 70 which encloses the generally cylindrical chamber 72 of the housing.

Within the chamber 72 is a helically coilable measuring rule 74 of tempered sheet steel and preferably constructed so as to automatically withdraw o'r coil the rule to a stored position preferably with the outer end of the rule extending forwardly of the housing a couple inches, as shown in FIG. 1, to facilitate its being grasped by the fool operator. The inner end of the coilable rule is secured, as by a screw fastener 75, to a stationary pin 78 integrally formed centrally within the generally cylindrical opening in the housing. The pin 78 may have a flattened edge and the housing may have an opposed opening for facilitating the securing of the inner end of the rule.

The housing 62 is provided with a guide slot 79 extending forwardly of and generally tangential to the from the spirit and scope of the invention, the scope .which is defined in the appended claims.

enclosed article.

Riveted adjacent the outer end of the coilable rule is a laterally extending clip or fastener 32 of tempered sheet steel and formed to provide a pair of resiliently engaging clip parts 84, 86. The illustrated clip is formed by reversely bending the sheet steel to provide a V-shaped intermediate clip part 34 with an apex engageable with an outer clip part '86. The clip is dimensioned to receive the strap for which purpose the clip parts are resiliently separable, with the resilient engagement with the strap being sufiicient for extending the rule and yet allow for manually sliding the clip on the strap for adjustment of the extension of the rule.

The coilable rule is used by clipping the rule to a loop of strap forwardly of the tensioning tool, preferably after all the slack in the loop has been taken up and before the loop has been placed under more than minimal tension. The clip is then attached to the loop with a predetermined length of strap between the clip and tool, and where necessary with the rule wrapped partly about the article enclosed by the loop of strap. For this purpose, appropriate indi-cia may be placed on the surface of the rule, which when in registration with a rule index 90, provided by the edge between the forward substantially fiat face of the rule housing 62 and the guide slot 79, indicates the extension of the rule and therefore the length of strap between the clip and the tensioning tool. With subsequent tensioning of the strap loop, the nonmetallic strap will undergo some lengthening or strain, with th strain being a function of the tension on the strap. Accordingly, indicia can be provided on the rule indicating the lengthening of the predetermined length of strap and therefore the tension of the strap. Preferably, the indicia take the form of colored rule sections 9-1 which can thereby 'be readily viewed by the tool operator, and with each color having a leading edge providing an indication of the selected length of strap and the trailing edge providing a measure of the tension of the strap. By using several colored sections difierent strap tensions can be indicated and/ or the rule can be useful with straps having different stress/ strain relationships.

Thus it can be seen that the extensometer facilitates the controlling of the strap tension by the convenient step of merely attaching the rule clip to the loop after the loop slack has been taken up and by sliding the clip along the loop until the appropriate indicia on the rule is in registration with the rule index 90. During the tensioning of'the loop of strap by the handle 3%, as soon as the appropriate indicia on the rule is viewed in registry with the index, the appropriate tension is obtained. The extensometer is useful with the banding of irregular shaped articles and with articles of large and small sizes without special calibration, and where the tensioning tool is to be used with various strapping materials, the rule can be appropriately calibrated in. advance by coloring appropriate sections of the ruleand thereby avoid subsequent technical or mathematical considerations by the operator of the tensioning device.

As will be apparent to persons skilled in the art, variousniodifications and adaptations of the structure above described will become readily apparent without departure of I claim:

1. In combination with a tensioning tool operable for tensioning a loop of nonmetallic strap with overlapping outer and inner strap portions and having a base and a tension wheel pivotally mounted outward of the base for receiving the overlapping strap portions therebetween, the tension wheel being pivotal into operative engagement with the outer strap portion for forward feeding of the outer strap portion with the inner strap portion being restrained, an extensometer comprising a coilablc metal rule having an inner end secured to the tensioning tool laterally of the tensioning wheel and an outer end extendable forwardly adjacent the loop of strap and laterally spaced therefrom, a laterally extending clip fixed to adjacent the outer end of the rule having a pair of resiliently separable clip portions adapted for resiliently retaining the strap therebetween, a rule index mounted on the tool, and indicia means on the rule cooperative with the index for positioning the clip on the strap a predetermined distance from the tool and for ascertaining the strap strain resulting from the subsequent operation of the tool.

2. In combination with a tensioning tool operable for tensioning a loop of nonmetallic strap with overlapping outer and inner strap portions and having a base adapted for receiving the inner strap portion, a loosely mounted support outward of the base adapted for receiving the outer strap portion, a tension wheel housing pivotally mounted outward of the support, a tension wheel rotatably mounted in the housing and pivotal with the housing into engagement with the outerlstrap portion for forwardly feeding the outer strap portion and with the support being urged inwardly for clamping the inner strap portion against the base, an extensometer comprising a coilable rule housing, fastener means fixing the rule housing to the tension wheel housing laterally of the tension wheel, the rule housing having a forward slot opening, a pin mounted centrally within the housing with its axis parallel to the axis of the tension wheel, a metal rule coilable within the housing with its inner end secured to the central pin and extending through said forward slot, clip means fixed adjacent the outer end of the rule for afiixing the rule to the strap loop, and indicia means on the rule for afiixing the clip on the strap loop a predetermined distance forwardly of the tensioning tool and for indicating the strap strain resulting from the subsequent operation of the tool.

3. In combination with a tension'mg tool operable for tensioning a loop of strap with overlapping outer and inner strap portions and having a base and a tension wheel mounted outward of the base for receiving the overlapping strap portions therebetween, the tension wheel being adapted for operative engagement with the outer strap portion for forward feeding of the outer strap portion with the inner strap portion being restrained, and extensorneter comprising an elongated measuring rule, means for mounting the measuring rule on the tensioning tool for movement forwardly of the tool parallel to and adjacent the loop of strap, clip means on the forward end of the elongated rule for attaching the forward end of the rule to the loop of strap, a rule index mounted on the tool, and indicia means on the rule cooperative with the index for positioning the clip means on the strap a predetermined distance from the tool and for providing a stress limit indicator for the following tensioning operation by the tensioning tool. 4

4. In combination with a tensioningtoolioperable for tensioning a loop of strap with overlappingrouter and inner strap portions and having a base and a tension wheel mounted outward of the base for receiving the overlapping strap portions therebetween, the tension wheel, being adapted for operative engagement with the outer strap portion for forward feeding of the outer strap portion with the inner strap portion being restrained, an extensometer comprising a coilable rule, means mounting the coilable rule on the tensioning tool for extension forwardly of the tool parallel to and adjacent the loop of strap, clip means on the forward end of the coilable rule for attaching the forward end of the rule to the loop of strap, a rule index mounted on the tool, and indicia means including colored sections along the rule cooperative with the rule index for positioning the clip means on the strap a predetermined distance from the tool and for providing stress limit indicators for the operation of the tool.

References Cited by the Examiner UNITED STATES PATENTS Moore 73-95 Scott 33-138 Miller 73-95 Coupland 254-51 Lingle 25451 X WILLIAM FELDMAN, Primary Examiner. MILTON s. MEHR, Examiner. 

3. IN COMBINATION WITH A TENSIONING TOOL OPERABLE FOR TENSIONING A LOOP OF STRAP WITH OVERLAPPING OUTER AND INNER STRAP PORTIONS AND HAVING A BASE AND A TENSION WHEEL MOUNTED OUTWARD OF THE BASE FOR RECEIVING THE OVERLAPPING STRAP PORTIONS THEREBETWEEN, THE TENSION WHEEL BEING ADAPTED FOR OPERATIVE ENGAGEMENT WITH THE OUTER STRAP PORTION FOR FORWARD FEEDING OF THE OUTER STRAP PORTION WITH THE INNER STRAP PORTION BEING RESTRAINED, AND EXTENSOMETER COMPRISING AN ELONGATED MEASUREING RULE, MEANS FOR MOUNTING THE MEASURING RULE ON THE TENSIONING TOOL FOR MOVEMENT FORWARDLY OF THE TOOL PARALLEL TO AND ADJACENT THE LOOP OF STRAP, CLIP MEANS ON THE FORWARD END OF ELONGATED RULE FOR ATTACHING THE FORWARD END OF THE RULE TO THE LOOP OF STRAP, A RULE INDEX MOUNTED ON THE TOOL, AN INDICIA MEANS ON THE RULE COOPERATIVE WITH THE INDEX FOR POSITIONING THE CLIP MEANS ON THE STRAP A PREDETERMINED DISTANCE FROM THE TOOL AND FOR PROVIDING A STRESS LIMIT INDICATOR FOR FOLLOWING TENSIONING OPERATION BY THE TENSIONING TOOL. 